CM 7281 VHF-UHF single inputCM 7282 VHF-UHF dual InputMATV Distribution AmplifiersIntroduction and ApplicationsThese fully screened amplifiers are ideal for handling TV and FM DAB radio signals in small and mediumsized MATV distribution systems. These amplifiers have a single output and are used in conjunctionwith a passive distribution network built using splitters and taps (also available from Labgear). Advice onthe design of suitable distribution networks is available from Labgear's technical support department ifrequired.CM 7281This is a single-input wideband amplifier covering Bands I to V (40-862 MHz). It should be usedwhere the signals from VHF and UHF antennas have been combined before reaching the amplifier.CM 7282This type has separate VHF and UHF inputs, each with its own gain control. Separate feeds from theantennas are required, but the ability to set VHF and UHF signal levels separately is an advantage. TheVHF operating frequency range of the CM 7282 has been configured for use in Bands I to 111(40-300MHz).Digital applicationsBoth units are suitable for handling digital terrestrial TV (DTT) signals in addition to the analogue services.Distribution of DTT signals requires careful attention to system design and to signal levels forsatisfactory results.Using a UHF pre-amplifierIn weak UHF signal areas, or where a long downlead cable run is required, it may be desirable to use amasthead preamplifier mounted close to the UHF antenna. These MATV amplifiers feature built-in12V input line-powering; there is no need to use a separate power unit for the masthead amplifier.--(Type CM 7282 has line-power on the UHF input only.)The built-in line-power is rated at 40mA (fully short-circuit proof) and is compatible with the majorityof Labgear masthead preamplifiers.Installation InstructionsThe preamplifier gain used should be kept to a minimum and generally only needs to exceed thedown lead cable loss by about 6dB. A single-stage 15dB gain masthead (PUM111) will be suitable forthe great majority of applications. Use of excessive amounts of gain will lead to severe cross-modulation and intermodulation problems.